zippyshare (download): fix (for files without captcha), upstream modified

Fixes issue 1035.
plowdown: detect (simple) redirection services

For example:
http://8bbd5066.redir.com/url/http://www.hoster.com/file/921AFF48
plowdown: fix, deal correctly with unresolved host error
bayfiles (download, probe): better dead link detection
download.sh (mark_queue): fix, unwanted newline for empty FILENAME

Bug was introduced in commit
download.sh (mark_queue): fix bug when filename contains an ampersand (&)
revision 0b261c1470357a367632bc280437ebe478fa4ab0
bayfiles (download, probe): fix filenames (translate HTML entities)